read one set of profile and rewrite profile contents. One
can scale or normalize the count values.

Examples of the use cases for this tool are:

*

Collect the profiles for different set of inputs, and use
this tool to merge them. One can specify the weight to factor in the
relative importance of each input.

*

Rewrite the profile after removing a subset of the gcda
files, while maintaining the consistency of the summary and the
histogram.

*

It can also be used to debug or libgcov code as the tools
shares the majority code as the runtime library.

Note that for the merging operation, this profile generated offline may contain
slight different values from the online merged profile. Here are a list of
typical differences:

*

histogram difference: This offline tool recomputes the
histogram after merging the counters. The resulting histogram, therefore,
is precise. The online merging does not have this capability -- the
histogram is merged from two histograms and the result is an
approximation.

*

summary checksum difference: Summary checksum uses a CRC32
operation. The value depends on the link list order of gcov-info objects.
This order is different in gcov-tool from that in the online merge. It's
expected to have different summary checksums. It does not really matter as
the compiler does not use this checksum anywhere.

*

value profile counter values difference: Some counter
values for value profile are runtime dependent, like heap addresses. It's
normal to see some difference in these kind of counters.

Display help about using gcov-tool (on the standard
output), and exit without doing any further processing.

-v

--version

Display the gcov-tool version number (on the
standard output), and exit without doing any further processing.

merge

Merge two profile directories.

-odirectory

--outputdirectory

Set the output profile directory. Default output directory
name is merged_profile.

-v

--verbose

Set the verbose mode.

-ww1,w2

--weightw1,w2

Set the merge weights of the directory1 and
directory2, respectively. The default weights are 1 for both.

rewrite

Read the specified profile directory and rewrite to a new
directory.

-nlong_long_value

--normalize <long_long_value>

Normalize the profile. The specified value is the max
counter value in the new profile.

-odirectory

--outputdirectory

Set the output profile directory. Default output name is
rewrite_profile.

-sfloat_or_simple-frac_value

--scalefloat_or_simple-frac_value

Scale the profile counters. The specified value can be in
floating point value, or simple fraction value form, such 1, 2, 2/3, and
5/3.

-v

--verbose

Set the verbose mode.

overlap

Compute the overlap score between the two specified profile
directories. The overlap score is computed based on the arc profiles. It
is defined as the sum of min (p1_counter[i] / p1_sum_all, p2_counter[i] /
p2_sum_all), for all arc counter i, where p1_counter[i] and p2_counter[i]
are two matched counters and p1_sum_all and p2_sum_all are the sum of
counter values in profile 1 and profile 2, respectively.

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the Front-Cover texts being (a) (see below), and with the Back-Cover Texts
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A GNU Manual

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